This invention relates to a bone resection guide for use in orthopedic surgery. More particularly, this invention relates to a tibial resection guide and a mechanism for allowing both coarse and fine adjustment of the resection guide without requiring repositioning of the surgeon's hand and without requiring any tightening of a locking knob to lock a pair of telescoping rods in place.
In total knee arthroplasty, particularly in the resection of the distal femur and proximal tibia, cutting blocks are positioned in close proximity to the bone and adjusted in either a proximal or distal direction to achieve a measured amount of resection determined by the surgeon. Once the cutting block is set in the desired resection level, it is locked in place to prevent movement during the cutting of the bone. Three methods of adjustment and locking are currently employed in achieving this surgical step.
In a first method, the height of resection is achieved by moving a telescoping rod which, itself, is attached to the cutting block in either a proximal or distal direction and subsequently locking it at a desired position by turning a threaded knob mounted in the outer tubular rod into engagement with an inner rod. A drawback of this method is that it does not provide a fine adjustment of the cutting block which is counted in millimeters and the position of the cutting block may slip, since the degree of locking is dependent on how tight the surgeon turns the thumbscrew. Some designs utilize a camlock mounted between the inner and outer telescoping portions to more Positively lock the rods together. Woolson U.S. Pat. No. 4,841,975 discloses a tibial resector guide having a telescoping rod carrying a cutting head at its upper end. The cutting guide is adjustable relative to the telescoping rod by a pair of oppositely positioned thumbscrews. The guide may be aligned with the mechanical axis of the joint by using a slidable plate.
Poggie et al. U.S. Pat. No. 5,002,547 and Petersen U.S. Pat. No. 4,524,766 disclose tibial resector guides wherein the cutting guides are fixed to a telescoping rod.
Dunn et al. U.S. Pat. No. 4,759,350 discloses a tibial resector guide having a fixed head carried by a telescoping rod. A separate pinning strap is carried by the rod adjacent the head. The strap is fixed to the telescoping rod.
Fargie et al. U.S. Pat. No. 4,736,737 discloses a tibial resector head connected to an intramedullary rod and shiftable in the longitudinal direction only.
U.S. Pat. No. 5,228,459 to Caspari et al. relates to a tibial resection guide having both a telescoping adjustment and a threaded adjustment.
U.S. Pat. No. 5,445,640 to Johnson et al. relates to a tibial resection guide which includes a thumbwheel for locking the telescoping rods in position and includes a length adjustment mechanism which provides small adjustments in the overall length of the tibial resector guide.